Blake has a point.
I cant find the rubber gas filler tubes for my stepside. I have one "custom" made that I did a few years ago on the PS, and now I need to do the same for my DS. Im just waiting for gas to spill out of the cracks. I know goodyear makes different sizes and bends, I just need to get my butt out and figure something out. Boat suppliers might be a possible solution as well. They carry large diameter rubber.
My stepside has gas doors as well and I will have to cut out the door when I get around to replacing my fender, unless a miracle happens and I come across someone parting a PS fender with door.
There was another option, more popular, with the gas cap exposed. Ugly IMO.